The 1-1 draw at Ashton gate on Tuesday night means the two sides will have to replay next week for a place in the next round.
City also have rearanged league fixtures to contend with over the coming weeks because of their postponement due to the recent bad weather.
However, Johnson was just pleased to still be in the Cup after substitute Gavin Williams grabbed a stoppage-time equaliser to earn a 1-1 draw against Cardiff.
"It looked as though we were going out of the FA Cup with a couple of minutes left and that was the last thing we wanted," he said after the match.
"It's a fantastic competition and we want to stay in it for as long as possible.
"I know it's another game we have to play and we said that was something we didn't want. But I'm happy to be going to Cardiff next week.
"If that means we have a fixture backlog, then I'm happy to cope with it. January and February are important months which will define the rest of our season and that late goal could kick-start us."
"We've seen enough late goals go in against us this season, so it was nice to see us score one in the 94th minute for a change."